// Pin 13 has an LED connected on most Arduino boards
int ledin = 11;
int ledex = 12;

void setup() {
  pinMode(ledin, OUTPUT);
  pinMode(ledex, OUTPUT);
  }

  void loop() {
    digitalWrite(ledin, HIGH);
    digitalWrite(ledex, LOW);   // turn the LED on (HIGH is the voltage level)
      delay(250);               // wait for a second
        digitalWrite(ledex, HIGH);
        digitalWrite(ledin, LOW);    // turn the LED off by making the voltage LOW
          delay(250);               // wait for a second
          }